Air Conditioning Systems
The earliest automobiles that surpassed horse drawn carriages had cabin spaces that were open to the environment. This resulted the attire of the occupants to be worn based on the weather conditions. Modern automobiles have their cabin closed. Early designs of closed cabin automobiles had to be monitored carefully and it required manual regulation of heating, cooling and ventilation.
“In 1939 Packard marketed the first mechanical automotive Air Conditioning system which worked on a closed cycle” (Daly 2006). This system consisted of a compressor, condenser, receiver drier and evaporator.
Typical automobile air conditioning systems consists the elements that were introduced in the 1939 mechanical car by Packard. The compressor is used to pressurize the refrigerant into superheated vapor which then passed through the condenser coils. The condenser is exposed to the air which is at a lower temperature than the refrigerant inside the condenser coils. This results in the transfer of heat from the refrigerant to the air. The refrigerant becomes a saturated liquid after it passes the coils while still being relatively hot with a high pressure. The expansion valve regulates the refrigerant entering the evaporator by a throttling process whereby which the refrigerant pressure drops causing the refrigerant to become a mixture of saturated liquid and vapor. The refrigerant then passes the evaporator which has air entering with a temperature higher than that of the refrigerant. The refrigerant, whilst maintaining the same temperature becomes a saturated vapor by absorbing the heat from the air. The air that enters the evaporator is from the refrigerated space. The removal of heat causes the cooler temperature in the refrigerated space of the automobiles.